Rotary cutting tool



Feb. 23, 1965 s. A. JOHNSON 3,170,224

ROTARY CUTTING TOOL Filed Jan. 15. 1964 A7- TORNEYS may be readily attached to and removed 3,177 53,224 RGTARY CUTTRNG TGGL Etanley A. .Iohnson, North Star Speciaities line,

8% 16th Ave. SE, Minneapolis, Filed Han. 15, 1964, Ser. No. 337,35

2 (Ilairns. {$1. 29 1fi5) My invention relates generally to metal working tools and more particularly to back-facing tools.

The primary object of my invention is the provision of an extremely inexpensive light weight tool bit which from conventional portable rotary power sources, such as chuckequipped hand drills and the like, and which may be used with a minimum consumption of time and effort to either deburr or chamfer metallic workpieces which have been previously drilled.

A further object of my invention is the provision of a device of the class above described which includes a shank having a bifurcated outer end in which is pivotally mounted a novel triangular combination deb-urring and chamfering head which has a maximum longitudinal dimension considerably greater than that of saidshaft and a minimum transverse or altitude dimension substantially equal to that of said shaft, whereby upon imparting pivotal movements of said head, same may be passed through an opening corresponding in diameter generally to that of said shaft and thereafter swung into alternative operative positions to either deburr and backface or chamfer.

A further object of my invention is the provision of a device of the class above described whichris extremely inexpensive to produce, which is foolproof in its operation, and which is rugged and durable.

The above and still further objects of my invention will become apparent from the following detailed specification, appended claims, and attached drawings.

Referring to the drawings wherein like characters indi- I cate like parts throughout the several views:

FIG. 1 is a view in perspective of my novel tool; FIG. 2 is a view in side'elevation of the structure of FIG. 1, showing a different position of some of the parts,

. some parts being broken away and shown in section;

FIG. 3 is a view corresponding to FIG. 2, but showing a still different position of some of the parts;

FIG. 4 is a view in transverse section as seen from the line 4-4 of FIG. 3;

FIG. 5 is a view in end elevation of the structureof FIG. 1; and

FIG. 6 is an enlarged fragmentary view in side elevation as seen generally from right to left of FIG. 1, some parts being broken away and shown in section.

Referring with greater particularly to the drawings, the numeral 10 indicates the shaft or shank of my novel tool, which, preferably, and as shown, is cylindrical in shape.

At its upper end, not shown, the shank 10 is. adapted to he received within the chuck of a conventional power tool such as a portable hand drill. At its outer endthe shaft 11) is bifurcated as at 11, the opposed tines; thereof being identifiedby 12. 'Snugly received between the tines 12 for free pivotal movements about the pin 13 is a cutting head 14. Head 14, as shown, is in the nature of an isosceles triangle, the flat opposite sides. thereof being identified by 15 and 16. Specifically, the converging side edges 17, 18 are each of a less dimension than the longitudinal dimension of the base 19. 1

It will be noted that the plane of the head 14' is mounted for pivotal movements in a plane bisecting the axis of the shaft 10, and that the pivot pin 13 passes through the 3,179,224 Patented Feb. 23, 1965 projected planes of the opposite sides 10a of the shaft 10 so as to permit passage of the head 14 through a drilled aperture X in a workpiece Y which hasdiametrical dimension only slightly greater than that of shaft 10. Thereafter, the head 14 may be rotated about the axis of the pivot pin 13 to either of its two operative positions, one of which is indicated by dotted lines in FIG. 2, and

the other by the full line showing of FIG. 3. 'Which of these two alternative positions is chosen,.would depend upon whether the operator desires to remove by back facing the burr Z, conventionally formed by the drilling of the aperture X, and as shown in FIG. 3, or alternatively, to chamfer the lower end of the aperture X, as indicated by 20 in FIG. 2.

As shown, the linear dimension ofv the base 19 of the cutting head 14 is substantially greater than the transverse dimension of the shaft 11). For the purpose of increasing the cutting ability of said base 19, opposite end portions 1%, 1% thereof are relieved rearwardiy of their respective cutting edges 21, 22.

It will be noted that the converging side edges 17, 1S of the cutting head 1 are likewise relieved rearwardly of their cutting edges 23, 24 defined respectively thereby, as indicated at 23a, 24a, respectively.

be completely satisfactory for the accomplishment of the.

above objects; and while I have disclosed a preferred em bodirnent thereof, same may well be capable of modification without departure from the scope and spirit of the appended claims.

What is claimed is: a V

1. A rotary metal working tool bit comprising:

(a) an elongated shaft having a bifurcated outer: end,

I (b) a cutting head in the form of an isosceles triangle, the base portion of which has a longitudinal dimension substantially greater than the transverse dimension of said shaft and which is formed to define flat parallel side surfaces,

(c) the converging sides of said cutting head defining cooperating cutting. edges, and opposite side portions of the base of said head defining cooperating substantially coplanar cutting edges,

(d) said cutting head being mounted in the bifurcated end of said shaft centrally along the altitude thereof for unlimited pivotal movements in a plane bisecting the axis of said shaft,

(e) the altitude of said cutting head having a dimension corresponding generally to the transverse dimension of said shaft, whereby said head may be substantially retracted into the projected planes "of opposite. sides of said shaft when said head is pivotally moved to an inoperative positionwith the base thereof in substantial alignment with one side of said shaft.

No references cited.

ANDREW JUI-IASZ. Primary Examiner. 

1. A ROTARY METAL WORKING TOOL BIT COMPRISING: (3) AN ELONGATED SHAFT HAVING A BIFURCATED OUTER END, (B) A CUTTING HEAD IN THE FORM OF AN ISOSCELES TRIANGLE, THE BASE PORTION OF WHICH HAS A LONGITUDINAL DIMENSION SUBSTANTIALLY GREATER THAN THE TRANSVERSE DIMENSION OF SAID SHAFT AND WHICH IS FORMED TO DEFINE FLAT PARALLEL SIDE SURFACES, (C) THE CONVERGING SIDES OF SAID CUTTING HEAD DEFINING COOPERATING CUTTING EDGES, AND OPPOSITE SIDE PORTIONS OF THE BASE OF SAID HEAD DEFINING COOPERATING SUBSTANTIALLY COPLANAR CUTTING EDGES, (D) SAID CUTTING HEAD BEING MOUNTED IN THE BIFURCATED END OF SAID SHAFT CENTRALLY ALONG THE ALTITUDE THEREOF FOR UNLIMITED PIVOTAL MOVEMENTS IN A PLANE BISECTING THE AXIS OF SAID SHAFT, (E) THE ALTITUDE OF SAID CUTTING HEAD HAVING A DIMENSION CORRESPONDING GENERALLY TO THE TRANSVERESE DIMENSION OF SAID SHAFT, WHEREBY SAID HEAD MAY BE SUBSTANTIALLY RETRACTED INTO THE PROJECTED PLANES OF OPPOSITE SIDES OF SAID SHAFT WHEN SAID HEAD IS PIVOTALLY MOVED TO AN INOPERATIVE POSITION WITH THE BASE THEREOF IN SUBSTANTIAL ALIGNMENT WITH ONE SIDE OF SAID SHAFT. 